4:15 PM - 4:30 PM
[MGI34-04] Isotope fractionation of Mo-like elements during adsorption to ferromanganese oxides
Keywords:molybdenum, ferromanganese oxide, isotope fractionation, quantum chemical calculation, vanadium, germanium
XAFS analysis indicated that the adsorbed species of Ge on Fe- and Mn-(oxyhydr)oxides have Td geometry. On the other hand, the adsorbed structure of V on ferrihydrite is Td whereas that on δ-MnO2 is distorted Oh. This trend of V in adsorbed species is similar to that of Mo. The geometries of hydrated species of Ge and V are Td. Thus, it is expected that a large V isotope fractionation occur during adsorption on Mn oxide, but a small fractionation in the case of Ge. In fact, a large isotope fractionation for V and a small isotope fractionation for Ge were estimated by quantum chemical calculations. This finding indicates that the requirement to show a Mo like large isotope fractionation during adsorption is not only an appropriate ionic radius. Recently, we found that two elemental properties of Mo(VI), namely d0 electronic configuration and appropriate ionic radius, lead to the large isotope fractionation. In fact, V(V) possesses d0 electronic configuration, but Ge(IV) does not. Tungsten (W)(VI) also satisfies the two properties and shows a large isotope fractionation during adsorption on Fe-/Mn-(oxyhydr)oxides. Thus, the elements which have the two elemental properties (Mo-like elements) can exhibit a Mo like large isotope fractionation during ferromanganese oxides.